This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project will examine the role of activity in controlling the excitability and morphology of neurons. We have succeeded in making conditional mice in which we can, in a cell autonomous manner, silence all excitatory input to that neuron, by deleting all AMPA and NMDA receptors. These neurons can then be studied over various time intervals after silencing to examine the effects on neuronal excitability and morphology.